Albert schmidt



A. SCHMIDT. SPARK PLUG AND METHOD OF FORMING THE SAME. APPLICATION FILED Nov.22. 1917.

1,308,872. Patented July 8, 1919.

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A Q J J Ewuewtoz attoznws STATES PATENT OFFICE.-

ALIBERT SCHMIDT, OF FLINT, MICHIGAN, ASSIGNOR TO CHAMPION IGNITION COMPANY, OF FLINT, MICHIGAN, A CORPORATION OF MICHIGAN.

SPARK-PLUG AND METHOD OF. FORMING THE SAME.

, Patented Jul 8, 1919.

Application filed November 2 2 1917. serau No. 206,297. 1

To all whom it may concern: I

Be -it known that I, ALBERT 'SoHMm'r, a citizen of the Republic of France, residing at Flint, in the county of Genesee and State of Michigan, haveinvented certain new and a useful Improvements in Spark-Plugs and Methods of Forming the Same, of which the following is a specification, reference being had therein to the accompanying drawings.

The invention relates to spark plugs designed for use in connection with highspeed explosion engines, and the invention consists in the construction and method of forming the same as hereinafter set forth.

In the drawings:

Figure 1 is a longitudinal section through V a spark-plug embodying my invention; and

Fig. 2 is a similar View showing the manner of engaging the insulator and compressing the same between the inner and outer sections of the case.

In the construction of-spark-plugs where subjected to high heat, as is the case when used on high-speed motors, it is diflicult to maintain insulation of the electrode and at the same time to dissipate the heat communicated thereto. Mica has been found to contain this dielectric property even where subjected to considerable heat, but with this material it is diflicult to maintain a gas-tight seal. With the present construction an effective seal is produced with mica insulation bycompressing this material between inner and outer casings, the electrode being seated in the inner casing. I have also devised a method of assembling these casings and the insulator, the construction being as follows: v

. A is the outer-casing of a spark-plug of any suitable external configuration, and having the usual threaded nipple B for engagement with the engine casing. The casing A is formed with tapering or conical inner face C of sufficient diameter to receive an insulating wall D and an inner metallic cas- -in Ewithin said wall. The inner casing E 18 also of tapering or conical form and-is forced into position by a longitudinal or axial movement with respect to the outer casing, which compresses the intermediate I insulation.

As shown in Fig. 1, the method of assembling 'these parts is to first cover the inner casing E with a wrapping of the mica or other insulating material which is inserted into the outer casing, then to ening this movement the space between the walls of the inner and outer casing 1s pro gressively contracted, with'a result that the insulator is highly compressed so as to form a hermetic seal. Moreover the compression will increase the density and thermal-conductivity of the insulator so as to provide for the ready transfer of heat from the inher casing to the outer. V

The inner casing E has a longitudinal bore therethrough for the passage of the shank F of the electrode. electrode has a head portion G with a tapering portion H between the same and the shank, which tapering portion is seated upon a correspondingly tapered portion I of the casing E to form a gas-tight seal. The head G is provided with a peripheral sharpened flange which extends into close proximity to an inturned annular flange K on the portion B of the casing, there being only suflicient space between to form a spark gap. The

insulator D base. portion L projecting inward beyond the end of the inner casing E and in contact with the wall of the outer casing, this portion forming the exposed insulating surface. M is a hollow insulator for the outer end of the plug, inclosing the outwardly-projecting portions ofthe electrode, insulator and inner casing, and N is a nut engaging the threaded end of the electrode shank and clampingthe insulator M.

' seated-upon the casmg E is in good heat conducting relation thereto. The inner casing, in turn, is in good heat conducting relation to the outer casing, as it is separated therefrom only by the highly compressed insulator which forms a good heat conductor. Thus the heat imparted to the electrode 3 is dissipated with suflicient rapidity to prevent danger of preignition.

What I claim as my invention is:

1. In a spark-plug, the combination with an outer casing, of an inner casing spaced therefrom, an insulator compressed between the outer and the inner casings, and an electrode extending through and removably seated in the inner casing and forming therewith a gas-tight seal.

:2. In a sparlcplug, the combination with an outer metallic casing, of an inner metallic casing, insulating material compressed between said inner and outer casings, and an electrode extending through and seated in the inner casing.

3. In a spark-plug, the combination with concentric inner and outer casings, one of said casings being of tapering form, insulating material compressed between said in ner and outer casings, and an electrode extending through and removably seated in said inner casing and forming therewith a gas-tight seal.

4:. In a spark-plug, the combination with an outer casing having a tapering inner face, of an inner casing having a tapering outer face, insulating material compressed between the tapering faces of said outer and inner casings, and an electrode extending through and'removably seated in the inner casing, said electrode forming a gas-tight seal with said inner casing.

5. In a spark-plug, the combination with an outer casing, of an inner casing displaced longitudinally with respect to said outer casing, insulating material between said inner and outer casings and overlapping the portion of the outer casing extending beyond the inner casing, and an electrode removably seated in said inner casing and forming therewith a gas-tight seal, said electrode having a head portion passing through the extension of said insulator, the periphery of the outer end of said head being in close proximity to said outer casing and forming a spark-gap.

In testimony whereofI aifix my signature.

ALBERT SCHMIDT. 

